This invention relates to the field of selective call radio receivers and more particularly to selective call personal paging radio receivers that have audio and visual alerting means.
In selective call radio paging systems, in particular those that store messages somewhere in the system for later communication to the recipient, each personal paging receiver ("pager") must be provided with some means to alert the pager user that a message is available. When a selective call transmission is received, the user is typically alerted by an audible alert tone or by a visual indication, such as a flashing light. Both audio and visual alert, however, have certain advantages and disadvantages. With audio alert the user is instantly aware that a message is available the moment the pager is selectively called, while with visual alert the user will only be aware of the message when he or she looks at the pager and observes the visual indication. On the other hand, audio alert can be annoying, especially to other people within listening range of the pager, while visual alert rarely interferes with conversations and meetings.
To enjoy the advantages of both audio and visual alert, prior part paging systems sometimes incorporate both into one pager. An extra switch is then added so that the user can select either audio and visual alert or visual alert only. The position of this extra switch then indicates the mode of operation of the pager. When only visual alert is selected, the pager is said to be operating in the "silent alert mode".
There are several disadvantages to such a prior art pager. The addition of the extra switch adds mechanical complexity to the pager and increases its cost. Furthermore, the recent market trend has been to reduce the overall size and weight of the pager. The addition of an extra switch, however, only adds to the pager's weight and requires additional space to mount the switch.